QBurst Technologies Software Engineer Interview Questions and Answers

Prototype chaining is the mechanism in JavaScript where an object inherits properties and methods from another object.

• In JavaScript, each object has a prototype property which points to another object. When a property is accessed on an object, if it doesn't exist on the object itself, JavaScript looks for it in the prototype chain.

• If the property is not found in the immediate prototype, JavaScript continues to loo...read more

Promises in Node.js are objects representing the eventual completion or failure of an asynchronous operation.

• Promises are used to handle asynchronous operations in a more readable and manageable way.

• They can be in one of three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() to handle success and .catch() to handle errors.

• Example: const myPromise = new Promise((resolve, reject) => { .....read more

Temporal dead zone is the period between entering scope and being able to access a variable.

• Occurs when trying to access a variable before it has been declared

• Caused by hoisting in JavaScript

• Results in a ReferenceError

• Example: accessing a let or const variable before its declaration

Merkle root is a hash value generated by hashing all the transactions in a block in a blockchain.

• Merkle root is used to efficiently verify the integrity of the transactions in a block.

• It is calculated by hashing the individual transactions in the block, then pairing and hashing those results until a single hash remains.

• Any change in the transactions will result in a different merkle root.

• Example: In a block contai...read more

Array methods in JavaScript are built-in functions that allow manipulation and traversal of arrays.

• Some common array methods include: map(), filter(), reduce(), forEach(), and find().

• map() - creates a new array by applying a function to each element in the original array.

• filter() - creates a new array with elements that pass a certain condition.

• reduce() - applies a function against an accumulator and each element ...read more